Activity in Level Three Warrants (Detail) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended
	Sep. 28, 2012	Sep. 30, 2011	Sep. 28, 2012	Sep. 30, 2011	Mar. 31, 2012
Class of Warrant or Right [Line Items]
Level 3 Warrants, beginning of period			$ 26,000	$ 732,000	$ 732,000
Change in fair value of warrant liability	4,000	(142,000)	(13,000)	(634,000)	(706,000)
Level 3 Warrants, end of period	$ 13,000		$ 13,000		$ 26,000